ABSTRACT
This chapter discusses the influence of maternal diabetes on the embryo at the preimplantation and preorganogenetic phase, the first week postfertilization in rodents and the first 2 weeks in man. The preimplantation period is a initial process of pregnancy when most women do not know that they are pregnant. Most studies on the effects of maternal diabetes on early pregnancy focused on the zygote, only few studies started to examine the oocytes. The mechanism of the developmental delay of the zygote is not clear. Several studies investigated the development of the zygote in diabetic rats. Leunda-Casi et al examined how high levels of glucose influence development of mouse blastocysts. Hyperglycemia induces excessive cell death in the inner cell mass of rat blastocysts, which was characterized mainly by nuclear fragmentation. Many studies on embryos, fetuses, and placentae from diabetic animals have demonstrated a variety of epigenetic changes, especially changes in gene expression and in DNA methylation induced by diabetic maternal environment.
